1. Field of the Invention
The present invention relates to an inkjet head and an inkjet printer using the same.
2. Description of the Related Art
There has been heretofore known an inkjet head of the type for driving a piezoelectric device to press ink packed in a pressure chamber adjacent to the piezoelectric device to eject ink from a nozzle connected to the pressure chamber toward a recording medium such as paper to thereby form an image on the recording medium.
For example, an inkjet head disclosed in JP-A-Hei3-150165 includes a cavity plate having columns of rhombic pressure chambers. A common electrode which is common to the pressure chambers of the cavity plate is provided on a pressure chamber side surface of the cavity plate in the inkjet head. A sheet-like piezoelectric device having individual electrodes (drive electrodes) corresponding to the pressure chambers is laminated on a surface of the cavity plate opposite to the pressure chamber side surface. The inkjet head is provided so that a drive voltage is applied between a certain individual electrode and the common electrode to displace the piezoelectric device toward the pressure chamber side to press ink in the pressure chamber to thereby eject ink from a nozzle connected to the pressure chamber.
Incidentally, in this type inkjet head, wiring from the individual and common electrodes to a drive circuit is complex because the common electrode is provided on a surface opposite to the individual electrodes. It is therefore conceived that lands separated from the individual electrodes are provided on the individual electrode side surface of the piezoelectric device so that the common electrode can be electrically connected to the lands through through-holes.
When the common electrode is connected to the lands through the through-holes in this manner, the individual and common electrodes can be electrically connected to the drive circuit without complex wiring except that a board having a wiring layer (pads) connected to the drive circuit is placed on a front surface of the piezoelectric device so that the individual electrodes and the lands are bonded to the wiring layer.
If the lands and the through-holes are provided on and in the piezoelectric device, the lands and the through-holes cause deformation unevenness of the piezoelectric device in regions in which the individual electrodes are adjacent to the lands. As a result, ink ejection characteristic varies in accordance with nozzles corresponding to the individual electrodes. If the connection routes (through-holes) for connecting the common electrode to the lands are provided as only one system in order to suppress deformation unevenness, durability/reliability of products is lowered because there is no preparatory wiring for accidents such breaking of wire.